Researchers achieve record pressure for solid iron

Aug 12, 2013 by Breanna Bishop
In a series of experiments, Lawrence Livermore National Laboratory researchers used the Omega laser system to compress iron up to 5.6 million atmospheres (5.6 million times the pressure at the Earth's surface), a record pressure for solid iron.

(Phys.org) —Iron is the most abundant element in Earth's core and the sixth most abundant element in the universe. As a key component of terrestrial planets and exoplanets, iron has been one of the most studied materials under extreme conditions.

In a series of campaigns led by the Lab's Yuan Ping using the OMEGA laser at the Laboratory for Laser Energetics (LLE) at the University of Rochester, researchers compressed iron up to 5.6 million atmospheres (5.6 million times the pressure at the Earth's surface), a record pressure for solid iron.

The record pressure is achieved by multi-. Using a series of shocks (rather than a single shock) keeps the entropy low while compressing the material, which is the key to keeping the temperature lower than the melting point and allowing the iron to remain solid.

Diagnosing the material properties under extreme conditions is as important as the creation of high-pressure states. The team employed an X-ray technique called EXAFS (extended X-ray absorption fine structure). EXAFS is a powerful tool widely used in but its application in materials under is still in its infancy. This work presents the first EXAFS data in high-energy-density (HED) matter.

Illustration of the experimental setup on the OMEGA laser. The team achieved a record high pressure for solid iron by multi-shock compression. The properties of iron are diagnosed by XAFS. Credit: X-ray absorption fine structure

The EXAFS data show that the close-packed structure of iron is stable in the regime explored, confirming simulation predictions and other experimental studies by X-ray diffraction up to 3 million atmospheres.

Unexpectedly, the team found that the temperature at peak compression is significantly higher than that from pure compressive work. Extra heat is generated by inelastic distortion of the lattice, termed plastic work. It is found that upon fast compression in a few billionths of a second, the strength of iron is enhanced, leading to more plastic work and the elevated temperature.

"It took us more than two years to develop this ." Ping said. "Now the measurements can be scaled up to larger laser systems, such as the National Ignition Facility, to reach higher pressures or extended to shorter time scale to study dynamics in HED materials."

The team's research appears in the August 9 issue of Physical Review Letters.

Explore further: Researchers study gallium to design adjustable electronic components

More information: prl.aps.org/abstract/PRL/v111/i6/e065501

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User comments : 9

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mkt1111
2.6 / 5 (5) Aug 12, 2013
What can be learned from this research?
antialias_physorg
4 / 5 (5) Aug 12, 2013
Take a wild guess (hint: think about where iron under that kind of pressure exists)
Lurker2358
4.5 / 5 (8) Aug 12, 2013
Take a wild guess (hint: think about where iron under that kind of pressure exists)


Translation:

It would help narrow down the true composition and density of planetary cores if you knew by experiment the exact configuration and density of iron under those conditions.
baudrunner
1.4 / 5 (10) Aug 12, 2013
This further supports the theory that the surface of the sun is comprised of a solid iron mantle. This theory explains also how cratered areas on the sun's surface maintain their integrity over time. (ref: http://www.thesur...un.com/)

I'm really tired of reading all the pseudo-science answers to these questions.

Example from Wiki Answers to "What is the sun's surface?" - "bit of helium, oxygen and other elements, but it's mostly hydrogen plasma." B.S.

Example from Yahoo Answers: "Since the Sun is a gas ball, there is no hard "surface" on which to set instruments to measure the pressure of the Sun's gasses" more B.S.

And from http://csep10.phys.utk.edu ! "The Sun is a ball of gas, so it does not have a well-defined surface. When we speak of the surface of the Sun, we normally mean the photosphere." my word!

How could an object so immense possibly maintain a gaseous state? Where are the scientists?!?!?
Protoplasmix
4 / 5 (4) Aug 12, 2013
This further supports the theory that the surface of the sun is comprised of a solid iron mantle

The pressure at the bottom of the photosphere is a whopping 285 mb (=0.281 atm), a far cry from the conditions of 5.6 million atm mentioned in the article.

Also there's differential rotation of the sun's surface. The period of rotation at the equator is 25 days, but nearer the poles it's slower, about 30 days. The surface is most certainly not solid.
GSwift7
5 / 5 (2) Aug 13, 2013
to reach higher pressures or extended to shorter time scale to study dynamics in HED materials


I'm going to assume they are talking about faster time resolution on their measurements when they say shorter time scales.

What can be learned from this research?


Antialias is correct about studying planetary cores, but there's a much more practical reason to do this. Based on simulations, we believe that many materials have exotic super-phases under extreme conditions. The properties of these super-phases could be things like frictionless fluids, very high temperature supercondutivity, ultra high tensile strength, catalytic properties, electrochemical or thermoelectric properties, etc. Some of these super-phases are believed to be stable at room temperature and pressure once you create them.

These kinds of materials will enable truely unimaginable jumps in what is possible to engineer in the future.
GSwift7
not rated yet Aug 13, 2013
You know, we haven't even scratched the surface of materials science. All the elements and the limitless combinations of them have properties that remain unknown to us, even under 'normal' conditions. Then they all have DIFFERENT properties when you break them down into various sizes and shapes of nano-sized particles and/or when they have nano surface textures. Then there's also a COMPLETELY DIFFERENT set of properties under extreme conditions. Then you ALSO can get totally different results when you combine the exact same ingredients with two different processes.
baudrunner
1 / 5 (3) Aug 13, 2013
The pressure at the bottom of the photosphere is a whopping 285 mb (=0.281 atm), a far cry from the conditions of 5.6 million atm mentioned in the article.


You didn't read the http://www.thesur...esun.com site one bit.

At sea level on Earth, atmospheric pressure is around 1,013 millibars. There is nothing "whopping" about that.

What's also important is what is not mentioned in the article, that researchers have been able to maintain iron's solid state at temperatures far exceeding those found on the surface of the sun.

Furthermore, from the site, "This image of FE IX/X (iron ion) emission from TRACE shows increased electrical activity on the surfaces that face toward the cosmic wind. The cosmic wind blows through the upper plasma layers resulting in differential rotation in the upper plasma layers, while the iron surface below rotates uniformly." (ref: http://thesurface...ing.htm)

READ!
RealScience
not rated yet Aug 18, 2013
This further supports the theory that the surface of the sun is comprised of a solid iron mantle


@baudrunner- reality check: the density of the sun (measured to the apparent surface) is 0nly 1.4 g/cc, or 6x less dense than iron (barely denser than water.